Important Machine Design Objective Questions For Competitive’s
1.The notch angle of the Izod impact test specimen is
10�
20�
30�
45�
60�.
ANSWER : : 45�
2.Stress concentration is caused due to
variation in properties of material from point to point in a member
pitting at points or areas at which loads on a member are applied
abrupt change of section
all of the above
none of the above.
ANSWER : : all of the above
3.Resilience of a material is important, when it is subjected to
combined loading
fatigue
thermal stresses
wear and tear
shock loading.
ANSWER : : shock loading.
4.Pick up wrong statement. Fatigue strength can be increased by
cold working
shot peening
grinding and lapping surface
hot working
using gradual changes of section.
ANSWER : : hot working
5.The property of a material which enables it to resist fracture due to high impact loads is known as
elasticity
endurance
strength
toughness
resilience.
ANSWER : : toughness
6.If a load W is applied instantaneously on a bar; then the stress induced in bar will
be independent of ratio of mass of load W to mass of bar (y)
increase with increase in y
decrease with decrease in y
depend on other considerations
none of the above.
ANSWER : : be independent of ratio of mass of load W to mass of bar (y)
7.Guest’s theory of failure is applicable for following type of materials
brittle
ductile
elastic
plastic
tough.
ANSWER : : ductile
8..Other method of reducing shock load in the above case can be
to decrease length
to increase length
unaffected by length
other factors would decide same
none of the above.
ANSWER : : to increase length
9.The pci Tnissible stress for carbon steel under static loading is generally taken as
2000-3000 kg/pm2
3000-4000 kg/cm2
4000-J500 kg/cm2
7500-10,000 kg/cm2
10,000-15,000 kg/cm2.
ANSWER : : 4000-J500 kg/cm2
10.Stress concentration in static loading is more serious in
ductile materials
brittle materials
equally serious in both cases
depends on other factors
unpredictable.
ANSWER : : brittle materials
11.Rankine’s theory of failure is applicable for following type of materials
brittle
ductile
elastic
plastic
tough.
ANSWER : : brittle
12.Which is correct statement ? Stress concentration in static loading is
very serious in brittle materials and less serious in ductile materials
very serious in ductile materials and less serious in brittle materials
equally serious in both types of materials
seriousness would depend on other factors
none of the above.
ANSWER : : very serious in brittle materials and less serious in ductile materials
13.The maximum stress due to stress concentration in a bar having circular transverse hole, as compared to its static stress without hole will be
same in both cases
2 times more
3 times more
4 times more
unpredictable.
ANSWER : : 3 times more
14.Which of the following is not correct procedure to increase the fatigue limit
cold working
shot peening
surface decarburisation
under-stressing
all of the above.
ANSWER : : surface decarburisation
15.Plastic flow in ductile materials
increases the seriousness of static loading stress concentration
lessens the seriousness of static loading stress concentration
has no effect on it
depends on other considerations
none of the above.
ANSWER : : lessens the seriousness of static loading stress concentration
16.A hot short metal is
brittle when cold
brittle when hot
brittle under all conditions
ductile at high temperature
hard when hot.
ANSWER : : brittle when hot
17.If an unsupported uniform cross sectional elastic bar is subjected to a longitudinal impact from a rigid bob moving with velocity v, then a compressive wave of intensity sc is propagated through the bar as follows
vpE
vVvF
WpE/2
IvHpE
none of the above, where E = modulus of elasticity and p = mass density.
ANSWER : : vpE
18.Coaxing is the procedure of increasing
metal strength by cycling
metal hardness by surface treatment
metal resistance to corrosion by coating
fatigue limit by overstressing the metal by successively increasing loadings
none of the above.
ANSWER : : fatigue limit by overstressing the metal by successively increasing loadings
19.Stress concentration in cyclic loading is more serious in
ductile materials
brittle materials
equally serious in both cases
depends on other factors
unpredictable.
ANSWER : : ductile materials
20.Endurance limit or fatigue limit is the maximum stress that a member can withstand for an infinite number of load applications without failure when subjected to
dynamic loading
static loading
combined static and dynamic loading
completely reversed loading
all of the above.
ANSWER : : completely reversed loading
21.Tensile strength of a mild steel specimen can be roughly predicted from following hardness test
Brinell
Rockwell
Vicker
Shore’s sceleroscope
none of the above.
ANSWER : s: a
22.Brittle coating technique is used for
determining brittleness
protecting metal against corrosion
protecting metal against wear and tear
experimental stress analysis
non-destructive testing of metals.
ANSWER : : experimental stress analysis
23.The fatigue life of a part can be improved by
electroplating
polishing
coating
shot peening
heat treating.
ANSWER : : shot peening
24.In the case of an elastic bar fixed at upper end and loaded by a falling weight at lower end, the shock load produced can be decreased by
decreasing the cross-section area of’ bar
increasing the cross-section area of bar
remain unaffected with cross-section area
would depend upon other factors
none of the above.
ANSWER : : decreasing the cross-section area of’ bar
25.The endurance limit of a material with finished surface in comparison to rough surface is
more
less
same
more or less depending on quantum of load
unpredictable.
26.A stud
has a head on one end and a nut fitted to the other
has head at one end and other end fits into a tapped hole in the other part to be joined
has both the ends threaded
has pointed threads
requires locking nuts.
ANSWER : : has both the ends threaded
26.Shear stress theory is applicable for
ductile fnaterials
brittle materials
elastic materials
all of the above
none of the above.
ANSWER : : ductile fnaterials
27.The building up of worn and uridersized parts, subjected to repeated loads by electroplating is
best method
extremely hazardous
has no effect as regards fatigue strength
cheapest method
all of the above.
ANSWER : : best method
28.If a material fails below its yield point, failure would be due to
straining
fatigue
creep
sudden loading
impact loading.
ANSWER : : fatigue
29.The endurance limit in shear of carbon steel can be obtained by multiplying the endurance limit in flexure by a factor of
0.25
0.45
.55
0.65
0.75.
ANSWER : : 0.75.
30.At low temperatures (say 75�C) the notched-bar impact value of steel
increases markedly
decreases markedly
remains same
depends on heat treatment carried out
none of the above.
ANSWER : : decreases markedly
31.Residual stress in materials
acts when external load is applied
becomes zero when external load is removed
is independent of external loads
is always harmful
is always beneficial.
ANSWER : s: c
32.Which is correct statement ? Stress concentration in cyclic loading is
very serious in brittle materials and less serious in ductile materials
very serious in ductile materials and less serious in brittle materials
equally serious in both types of materials
seriousness would depend on other factors
none of the above.
ANSWER : : equally serious in both types of materials
33.For steel, the ultimate strength in shear as compared to ultimate strength in tension is same
1/2
1/3
1/4
2/3
ANSWER : : 2/3
34.For applications involving high stresses in one direction only the following type of thread would be best suited
ISO metric thread
acme thread
square thread
buttress thread
British Association thread.
ANSWER : : buttress thread
35.In nitrided parts, the origins of the fatigue cracks will occur at
surface
just below the surface
within the core
could occur anywhere
none of the above.
ANSWER : : none of the above.
36.The ratio of endurance limit in shear to the endurance limit in flexure is
0.33
0.4
0.5
0.55
0.6
ANSWER : : 0.55
37.The crest diameter of a screw thread is same as
major diameter
minor diameter
pitch diameter
core diameter
none of the above.
ANSWER : : major diameter
38.Cold working
increases the fatigue strength
decreases the fatigue strength
has no influence on fatigue strength
alone has no influence on fatigue strength
none of the above.
ANSWER : : increases the fatigue strength
39.In most machine members, the damping capacity of the material should be
low
zero
high
could be anything
none of the above.
ANSWER : s: c
40.Which is correct statement ?
a member made of steel will generally be more rigid than a member of equal load-carrying ability made of cast iron
a member made of cast iron will generally be. more rigid than a member of equal load carrying ability made of steel
both will be equally rigid
which one is rigid will depend on several other factors
none of the above.
ANSWER : : a member made of cast iron will generally be. more rigid than a member of equal load carrying ability made of steel
41.A tap bolt
has a head on one end and a nut fitted to the other
has head at one end and other end fits into a tapped hole in the other part \o be joined
has both the ends threaded
has pointed threads
requires locking devices.
ANSWER : : has head at one end and other end fits into a tapped hole in the other part \o be joined
42.A bolt
has a head on one end and a nut fitted to the other
has head at one end and other end fits into a tapped hole in the other part to be joined
has both the ends threaded
is provided with pointed threads
requires no nut.
ANSWER : : has a head on one end and a nut fitted to the other
43.Resistance to fatigue of a material is measured by
Young’s modulus
coefficient of elasticity
elastic limit
ultimate tensile strength
endurance limit.
ANSWER : : endurance limit.
44.The fatigue limit of a material
is greatly decreased by poor surface conditions
remains same irrespective of surface conditions
depends mainly on core composition
is dependent upon yield strength of material
none of the above.
ANSWER : : is greatly decreased by poor surface conditions
45.If d is the diameter of bolt hole then for a flanged pipe joint to be leak proof, the circumferential pitch of the bolts should be
lOVZ
10VZtol5Vd
15Vdto20VZ
20Vdto30Vd
30V5″to40Vd.
ANSWER : : 20Vdto30Vd
46.Maximum principal stress theory is applicable for
ductile materials
brittle materials
elastic materials
all of the above
none of the above.
ANSWER : : brittle materials
47.Which process will increase the fatigue duration of parts ?
finishing and polishing
shot-peening
decarburisation
electroplating
all of the above”.
ANSWER : : shot-peening
48.The following type of nut is used with alien bolt
alien nut
hexagonal nut
slotted nut
castle nut
any one of the above.
ANSWER : : any one of the above.
49.Yield point in fatigue loading as compared to static loading is
same
higher
lower
depends on other factors
none of the above.
ANSWER : : lower
50.Eye bolts are used for
foundation purposes
locking devices
absorbing shock and vibrations
transmission of power
lifting and transportation of machines and cubicles.
ANSWER : : lifting and transportation of machines and cubicles.
51.Turn buckle has
right hand threads on both ends
left hand threads on both ends
left hand threads on one end and right hand threads on other end
no threads
threads in middle portion.
ANSWER : : left hand threads on one end and right hand threads on other end
52.Machine screws are
similar to small size tap bolts except that a greater variety of shapes of heads are available
slotted for a screw driver and generally used with a nut
used to prevent relative motion be-tween two parts
similar to stud
none of the above.
ANSWER : : slotted for a screw driver and generally used with a nut
53.The designation M 33 x 2 of a bolt means
metric threads of 33 nos in 2 cm.
metric threads with cross-section of 33 mm
metric threads of 33 mm outside diameter and 2 mm pitch
bolt of 33 mm nominal diameter having 2 threads per cm
none of the above.
ANSWER : : metric threads of 33 mm outside diameter and 2 mm pitch
54.If the tearing efficiency of a riveted joint is 75%, then the ratio of diameter of rivet to the pitch is equal to
0.2
0.25
0.50
0.6
0.75.
ANSWER : : 0.25
55.A key capable of tilting in a recess milled out in a shaft is known as
wood-ruff key
feather key
flat saddle key
gib head key
hollow saddle key.
ANSWER : : wood-ruff key
56.In order to obtain bolt of uniform strength
increase shank diameter
increase its length
drill an axial hole through head upto threaded portion so that shank area is equal to root area of thread
tighten die bolt properly
all of the above.
ANSWER : : drill an axial hole through head upto threaded portion so that shank area is equal to root area of thread
57.The function of a washer is to
provide cushioning effect
provide bearing area
absorb shocks and vibrations
provide smooth surface in place of rough surface
act as a locking device.
ANSWER : : provide bearing area
58.Fibrous fracture occurs in
ductile material
brittle material
elastic material
hard material
all of the above.
ANSWER : : ductile material
59.An alien bolt is
self locking bolt
same as stud
provided with hexagonal depression in head
used in high speed components
provided with countersunk head.
ANSWER : : provided with hexagonal depression in head
60.Transverse fillet welded joints are designed for
tensile strength
compressive strength
shear strength
bending strength
torsional strength.
ANSWER : : tensile strength
61.A self locking screw has
fine threads
coarse threads
coefficient of friction > tangent of load angle
hole for inserting split pin
two nuts for locking.
ANSWER : : coefficient of friction > tangent of load angle
62.Ball bearing type screws are found in following application
screw jack
aeroplane engines
crane
steering mechanism
bench vice.
ANSWER : : steering mechanism
63.The pitch of threads on a Jock nut in comparison to pitch of nut is
same
coarser
finer
very coarse
very fine.
ANSWER : : same
64.Rivets are generally specified by
thickness of plates to be riveted
length of rivet
diameter of head
nominal diameter
all of the above.
ANSWER : s: d
65.A key made from a cylindrical disc having segmental cross-section, is known as
wood-ruff key
feather key
flat saddle key
gib head key
hollow saddle key.
ANSWER : : wood-ruff key
66.Jam nut is a locking device in which
one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
a slot is cut partly in middle of nut and then slot reduced by tightening a screw
a hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is screwed on the bolt causing a tight grip
through slots are made at top and a cotter-pin is passed through these and a hole in the bolt, and cotter splitted and bent in reverse direction at other end
none of the above.
ANSWER : : one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
67.A tapered key which fits in a keyway in the hub and is flat on the shaft, is known as
wood-ruff key
feather key
flat saddle key
gib head key
hollow saddle key.
ANSWER : : flat saddle key
68.Buttress threads are usually found on
screw cutting lathes
feed mechanisms
spindles of bench vices
screw jack
railway carriage couplings.
ANSWER : : railway carriage couplings.
69.Which of the following is a permanent fastening ?
bolts
keys
cotters
rivets
screws.
ANSWER : : rivets
70.The edges of a boiler plate are beveled to an angle of
30�
45�
60�
80�
85�.
ANSWER : : 80�
71.The deflection of a cantilever beam under load W is 8. If its width is halved, then the deflection under load W will be
28
8/2
48
8/4
none of the above.
ANSWER : : 48
72.Cap screws are
similar to small size tap bolts except that a greater variety of shapes of heads are available
slotted for a screw driver and generally used with a nut
used to prevent relative motion be-tween parts
provided with detachable caps
similar to stud.
ANSWER : : similar to small size tap bolts except that a greater variety of shapes of heads are available
73.In order to avoid tearing of the plate at edge, the distance from the center line of the rivet hole to the nearest edge of the plate in terms of dia. of rivet d should be equal to
d
1.25 d
1.5 d
1.75 d
2 d.
ANSWER : : 1.5 d
74.Set screws are
similar to small size tap bolts except that a greater variety of shapes of heads are available
slotted for a screw driver and generally used with a nut
used to prevent relative motion be-tween parts
similar to stud
none of the above.
ANSWER : : used to prevent relative motion be-tween parts